Hi all, I'd like to bring up a discussion about removing registration of TableSource and TableSink in TableEnvironment as well as in ConnectTableDescriptor. The affected method would be:
TableEnvironment::registerTableSource TableEnvironment::fromTableSource TableEnvironment::registerTableSink ConnectTableDescriptor::registerTableSource ConnectTableDescriptor::registerTableSink ConnectTableDescriptor::registerTableSourceAndSink (Most of them are already deprecated, except for TableEnvironment::fromTableSource, which was intended to deprecate but missed by accident). FLIP-64 [1] already explained why we want to deprecate TableSource & TableSink from user's interface. In a short word, these interfaces should only read & write the physical representation of the table, and they are not fitting well after we already introduced some logical table fields such as computed column, watermarks. Another reason is the exposure of registerTableSource in Table Env just make the whole SQL protocol opposite. TableSource should be used as a reader of table, it should rely on other metadata information held by framework, which eventually comes from DDL or ConnectDescriptor. But if we register a TableSource to Table Env, we have no choice but have to rely on TableSource::getTableSchema. It will make the design obscure, sometimes TableSource should trust the information comes from framework, but sometimes it should also generate its own schema information. Furthermore, if the authority about schema information is not clear, it will make things much more complicated if we want to improve the table api usability such as introducing automatic schema inference in the near future. Since this is an API break change, I've also included user mailing list to gather more feedbacks. Best, Kurt [1] https://cwiki.apache.org/confluence/display/FLINK/FLIP-64%3A+Support+for+Temporary+Objects+in+Table+module
